October I. 1916. 



THE INDIA RUBBER WORLD 



21 



FIRESTONE "GIANT" SOLID RUBBER TIRES. 



There are certain conditions of service under which a .single 

 solid tire is superior to two tires fitted as twins on wheels of 

 heavy motor trucks. 



The Firestone Tire & Rub- 

 ber Co., Akron, Ohio, is sell- 

 ing "Giant" single tread solid 

 rubber tires in 8-inch, 10-inch 

 and 12-inch sizes. 



These massive single tread 

 tires have deep grooves in the 

 tread to provide against side- 

 slipping and are said to be as 

 near pneumatic resiliency as 

 can be produced in solid tire 

 form. 



It is claimed that this con- 

 struction gives a greatly in- 

 creased rubber cushion under 

 the load, with a saving in 

 weight in rim parts. Their 

 very appearance certainly sug- 

 gests strength and durability. 

 It is understuo'l that the X-incii "Giant" is considered as an 

 oversize for 4-incii and eQual to S-inch twin tires, the 10-inch 

 being oversize for 5-inch and equal to 6-inch twins, while the 

 12-inch "Giant" is oversize for 6-inch and equal to 7-inch twins. 

 These large tires are said to present a great advantage in uni- 

 formity of wear. They adjust themselves to the unevennesses 

 of the road, and are built with a broad base to insure better trac- 

 tion when the vehicle has a tendency to skid. The manufacturers 

 anticipate that this form of tire will come rapidly into wider 

 use. [Firestone Tire & Rubber Co., Akron, Ohio.] 



THE FEAR-NAUGHT TUBELESS TIRE. 



This is a tubeless piKiimatic tire tliat seems to be immune 

 Srom n\any of the troubles that threaten the pneumatic tire of 

 ordinary construction. It is said to be proof against blow-outs, 

 due to the sturdy character of the casing, and liability to puncture 

 is greatly minimized by the unusual thickness of the tread. 

 Moreover, should a puncture actually occur, the tire will continue 

 to carry the load without rim cutting, as it is non-collapsible. 



It is really a single tul)e tire divided in the center by an an- 

 nular rib of rubber, forming two continuous air chambers that 



are inflated through an 



nary type that opens 

 into both chambers. 

 Only one-half of the air 

 pressure required for 

 an average tire is recom- 

 mended for this one. It 

 is without beads, attach- 

 STEEL fliM j,^p,,j f^ jl^g j-ij,^ being 



made by eight threaded 

 lugs that are vulcanized 

 in the tire. These pass 

 through the rim and 

 when the nuts are tight- 

 ened the tire is securely 

 held in place against a 

 rubber liner of annular 

 form that occupies the bead space in the rim. They are made 

 in all sizes to fit clincher and quick demountable rims. The 

 Department of Militia and Defence of Canada has tested these 

 tires with the view of adopting them for military use. The 

 l>rototype of this tire was illustrated and described in The India 

 Rubber World, February 1, 1904. [Fear-Naught Tire Co., 

 I'aleriirvn, New Jersey.] 



WOOD FELLY 



VPiLVe STEM 



THE DUOO PNEUMATIC TIRE GAGE. 



This new English device possesses some novel advantages that 

 will appeal at once to the motorist who realizes the itnportance 

 of keeping his tires properly inflated. It is, in fact, a combined 

 air pump connection and pressure gage. 



It is used in the following 

 manner : The wheel is 

 turned so that the tire 

 valve occupies the highest 

 possible point, the valve 

 stem, therefore, extending 

 downward. The upper part 

 of the device is then slipped 

 over the stem and the air 

 turned on. While the tire 

 is being inflated the air 

 does not come in contact 

 at all with the gage. When 

 it is desired to know if the 

 tire is fully inflated, a 

 valve is operated by press- 

 ing the button at the end 

 111 the valve stem and the pressure of air in the tire is imme- 

 diately shown by a hand that points to the figures on the dial 

 .gage, indicating the tire pressure. Upon removing the hand 

 pressure from the button the air is at once diverted from the 

 gage and passes directly into the tire. [Brown Brothers, London, 

 England. 1 



METHOD OF DETERMINING AIR PRESSURE IN TIRES. 



Many tires tliat pass on to the scrap heap are prematurely 

 and needlessly' worn out through under-inflation. The amount 

 of air necessary to carry will depend upon the amount of work 

 that is to be done and the load carried. The following method 

 for determining the correct air pressure for different loads is 

 suggested by the Fisk Rubber Co. : 



Tlie motorist should determine the load for each tire and 

 regulate his air pressure to carry that load without injury to the 

 tire. To do this, weigh front and rear of the loaded car sepa- 

 rately, and divide by two, which will give the weight carried on 

 each wheel. 



Now that the weight of load carried by each wheel is known, 

 determine the air pressure by using the factor given opposite the 

 tire size to divide the amount of the load, the result being the 

 pressure required : 



.^-inch tire Divide weight of load by 8 



3^-inch tire Divide weight of load by 10 



4-inch tire Divide weight of load by 12 



4yi-inch tire Divide weight of load by 14 



5-inch tire Divide weight of load by 16 



5,'/^-inch tire. Divide weight of load by 18 



Example. — On a 4-inch tire you find the load to be 720 pounds. 

 Refer to above table and note that on a 4-inch tire 12 is the 

 factor: 720 pounds divided by 12 equals 60. therefore inflate the 

 tire to 60 pounds air pressure. 



As the load carried by the front tires is usually less than on 

 the rear, by using the method as suggested, it will be determined 

 that less air pressure is needed. The ideal load for the best all 

 around results under average conditions is as follows : 



.^-inch tires 400 pounds 



3 J;^-inch tires 550 pounds 



4-inch tires 735 pounds 



4J^-inch tires 960 pounds 



5-inch tires 1,210 pounds 



5Vj-inch tires 1,485 pounds 



A load heavier than these figures may be carried, but the re- 

 sulting pressure necessary to get good tire mileage is usually 

 very hard on the car and its occupants. To obtain best results 

 weigh car as suggested, divide any load by figure given and in- 

 flate to that amount ; test air pressure at least once a week. 



